A hard disk device (HDD) is a magnetic recording device used for storing information. In general, information is recorded on concentric tracks present on any one of both surfaces of one or more magnetic recording disks. A disk is rotatably supported by a spindle motor. Writing information on the tracks and reading out information from the tracks are carried out by a recording/reproducing head equipped to an actuator arm. The actuator arm is rotated by a voice coil motor. The voice coil motor is excited by electric current, and causes an actuator to rotate, and the recording/reproducing head to move. The recording/reproducing head makes out information by sensing the change of a magnetic field from the surface of the disk. In order to record data on the tracks, electric current is supplied to the recording/reproducing head. The electric current supplied to the recording/reproducing head cause a magnetic field to occur, which magnetizes the surface of the disk.
In recent years, accompanied with a technological evolution of methods for attacking security by a hacker, security of an external storage medium such as a hard disk device has been improved. In a known hard disk device, the HDD password is supported by an advance technology attachment (ATA) security command, which contributes to protect data in the hard disk device. In some cases, however, the HDD password may be broken by a hacker's analysis of firmware of the hard disk device and large scale integrated circuit (LSI).
In order to address such a problem, in recent years, the Seagate company has been proposed a technology called Full Disk Encryption (hereinafter referred to as “FDE”) (for example, http dot dot slash slash fde dot seagatestorage dot corn slash). FDE has a function to encrypt all of the data on the disk using an encryption key, thereby improving security of the data.
In such a FDE, unless the encryption key is known, even if the data on the disk is directly read out, the data cannot be decrypted. Moreover, FDE has an advantage in that, even if the HDD password is broken by means of operation of firmware and LSI, the data on the disk cannot be decrypted unless the encryption key is decrypted.
However, in FDE, since the encryption key is set in advance before a HDD or a system is shipped, there exists a problem that a user cannot change the encryption key. The user therefore has to use the encryption key set before the HDD is shipped and without changing it. As such, if the data in the HDD is stolen, the possibility exists the management of the HDD manufacturer responsible for the encryption key before shipping will be charged.
In view of the foregoing, a need has been recognized in connection with improving upon the shortcomings and difficulties of conventional efforts so that an encryption key may be changed easily and in a high speed when data recorded on a magnetic recording medium is encrypted using the encryption key.